Semiconductor light emitting device

ABSTRACT

A semiconductor light emitting device includes a light-emitting structure including a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer, a first transparent electrode layer on the second conductivity-type semiconductor layer, a first insulating layer on the first transparent electrode layer, the first insulating layer including a plurality of through-holes, a reflective electrode layer on the first insulating layer and connected to the first transparent electrode layer through the plurality of through-holes, and a transparent protection layer covering upper and side surfaces of the reflective electrode layer, the transparent protection layer being on a portion of the first insulating layer.

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2018-0009229, filed on Jan. 25, 2018,in the Korean Intellectual Property Office, and entitled: “SemiconductorLight Emitting Device,” is incorporated by reference herein in itsentirety.

BACKGROUND 1. Field

The present disclosure relates to a semiconductor light emitting device.

2. Description of the Related Art

Semiconductor light emitting devices are commonly known asnext-generation light sources due to inherent advantages thereof, e.g.,relatively long lifespans, low power consumption, fast response times,and environmental friendliness, as compared to conventional lightsources. In addition, semiconductor light emitting devices are prominentas important light sources in various products, e.g., illuminationapparatuses or in the backlights of display devices.

SUMMARY

According to an example embodiment, a semiconductor light emittingdevice may include a light-emitting structure including a firstconductivity-type semiconductor layer, an active layer, and a secondconductivity-type semiconductor layer, a first transparent electrodelayer on the second conductivity-type semiconductor layer, a firstinsulating layer on the first transparent electrode layer and includinga plurality of through-holes, a reflective electrode layer on the firstinsulating layer and connected to the first transparent electrode layerthrough the plurality of through-holes, and a transparent protectionlayer covering upper and side surfaces of the reflective electrodelayer, the transparent protection layer being on a portion of the firstinsulating layer.

According to an example embodiment, a semiconductor light emittingdevice may also include a light-emitting structure having a laminatestructure of a first conductivity-type semiconductor layer, an activelayer, and a second conductivity-type semiconductor layer and having arecess region in which the second conductivity-type semiconductor layer,the active layer, and a portion of the first conductivity-typesemiconductor layer are etched and a mesa region disposed adjacent tothe recess region, a first transparent electrode layer disposed on thesecond conductivity-type semiconductor layer, a first insulating layercovering the first transparent electrode layer and having a plurality ofthrough-holes disposed in the mesa region, a second transparentelectrode layer disposed on the first insulating layer and in contactwith the first transparent electrode layer through the plurality ofthrough-holes, a reflective electrode layer disposed on the secondtransparent electrode layer, and a transparent protection layer coveringupper and side surfaces of the reflective electrode layer and disposedon a portion of the first insulating layer.

According to an example embodiment, a semiconductor light emittingdevice may also include a substrate, at least one light-emittingstructure including a first conductivity-type semiconductor layer, anactive layer, and a second conductivity-type semiconductor layer,sequentially stacked on the substrate, a first transparent electrodelayer connected to the second conductivity-type semiconductor layer, afirst insulating layer partially covering the first transparentelectrode layer, a second transparent electrode layer passing throughthe first insulating layer and connected to the first transparentelectrode layer, a reflective electrode layer connected to the secondtransparent electrode layer, a transparent protection layer coveringupper and side surfaces of the reflective electrode layer and disposedon a portion of the first insulating layer, a first connection electrodepassing through the active layer and the second conductivity-typesemiconductor layer and connected to the first conductivity-typesemiconductor layer, and a second connection electrode passing throughthe transparent protection layer and connected to the reflectiveelectrode layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail exemplary embodiments with reference to the attached drawings,in which:

FIG. 1 illustrates a schematic plan view of a semiconductor lightemitting device according to an example embodiment;

FIG. 2 illustrates a schematic cross-sectional view along line I-I′ ofFIG. 1;

FIGS. 3A and 3B illustrate partially enlarged views of an area A of FIG.2;

FIGS. 4 and 5 illustrate schematic cross-sectional views ofsemiconductor light emitting devices according to modified exampleembodiments;

FIG. 6 illustrates a schematic cross-sectional view of a semiconductorlight emitting device according to another modified example embodiment;

FIGS. 7, 9, 11, 13, 15, 17, and 19 illustrate schematic plan views ofstages in a method of fabricating a semiconductor light emitting deviceaccording to an example embodiment;

FIGS. 8, 10, 12, 14, 16, 18, and 20 illustrate schematic cross-sectionalviews of along line I-I′ of corresponding FIGS. 7, 9, 11, 13, 15, 17,and 19; and

FIG. 21 illustrates a schematic cross-sectional view of an example of apackage including a semiconductor light emitting device according to anexample embodiment.

DETAILED DESCRIPTION

Hereinafter, example embodiments will be described with reference to theaccompanying drawings.

FIG. 1 is a plan view schematically illustrating a semiconductor lightemitting device 10 according to an example embodiment, and FIG. 2 is across-sectional view schematically illustrating an area taken along lineI-I′ of FIG. 1.

First, the semiconductor light emitting device 10 according to theexample embodiment is described with reference to FIGS. 1 and 2.

Referring to FIGS. 1 and 2, the semiconductor light emitting device 10according to the example embodiment may include a substrate 105, alight-emitting structure 110, a first insulating layer 130, a secondinsulating layer 150, a third insulating layer 160, a first transparentelectrode layer 140, a second transparent electrode layer 142, areflective electrode layer 144, a transparent protection layer 138, afirst connection electrode 155 n, a second connection electrode 155 p, afirst electrode pad 165 n, a second electrode pad 165 p, a first solderpillar 170 n, and a second solder pillar 170 p.

The substrate 105 may have a front surface 105 s 1 and a rear surface105 s 2 opposed to the front surface 105 s 1. The substrate 105 may be asubstrate for growing a semiconductor material, and may be formed of aninsulating material, a conductive material, or a semiconductor material,e.g., sapphire, Si, SiC, MgAl₂O₄, MgO, LiAlO₂, LiGaO₂, or GaN. Thesapphire may be used as a substrate for growing a nitride semiconductormaterial.

Throughout this disclosure, although terms such as “front surface” and“rear surface” may be used to describe the relationship of one elementto another, embodiments are not be limited by these terms. Accordingly,terms such as “front surface” and “rear surface” may be replaced byterms such as “first surface” and “second surface” or terms such as“upper surface” and “lower surface” to describe elements in thedisclosure. Accordingly, the front surface 105 s 1 of the substrate 105and the rear surface 105 s 2 may be replaced by an upper surface 105 s 1and a lower surface 105 s 2 of the substrate 105, or a first surface 105s 1 and a second surface 105 s 2 of the substrate 105.

The light-emitting structure 110 may be disposed on the front surface105 s 1 of the substrate 105. In some example embodiments, the frontsurface 105 s 1 of the substrate 105 may have a concavo-convexstructure, which improves crystallinity of semiconductor layersconfiguring the light-emitting structure 110 and light emissionefficiency of the light-emitting structure 110. In the exampleembodiment, the concavo-convex structure of the front surface 105 s 1 ofthe substrate 105 may have a dome-like convex shape, but is not limitedthereto. For example, the concavo-convex structure of the front surface105 s 1 of the substrate 105 may have a variety of shapes, e.g., atetragonal shape or a triangular shape. In addition, the concavo-convexstructure of the front surface 105 s 1 of the substrate 105 may beselectively formed or omitted.

In some example embodiments, the substrate 105 may be removed in asubsequent process. For example, the substrate 105 may be provided as agrowth substrate for growing the light-emitting structure 110 and thenremoved through a separation process. The substrate 105 may be separatedfrom the light-emitting structure 110 by a laser lift-off (LLO) method,a chemical lift-off (CLO) method, or the like.

Although not illustrated in the drawings, a buffer layer may be furtherformed on the front surface 105 s 1 of the substrate 105. The bufferlayer may serve to reduce lattice defects of the semiconductor layersgrown on the substrate 105, and may be formed of an undopedsemiconductor layer including a nitride material. The buffer layer mayinclude, e.g., undoped GaN, AlN, InGaN, or the like, and may be grown toseveral tens to several hundreds of angstroms (Å) at a low temperaturein the range of 500° C. to 600° C. Here, the term “undoped” means thatthe semiconductor layer is not subjected to a separate impurity-dopingprocess. However, the buffer layer may be omitted in some exampleembodiments.

The light-emitting structure 110 may include a first conductivity-typesemiconductor layer 115, an active layer 120, and a secondconductivity-type semiconductor layer 125. For example, the firstconductivity-type semiconductor layer 115, the active layer 120, and thesecond conductivity-type semiconductor layer 125 may be directly stackedon the substrate 105 in the stated order.

The first conductivity-type semiconductor layer 115 may be grown fromthe front surface 105 s 1 of the substrate 105. The firstconductivity-type semiconductor layer 115 may be a semiconductor layerdoped with n-type impurities, e.g., an n-type nitride semiconductorlayer.

In a plan view, the first conductivity-type semiconductor layer 115 mayhave a quadrangular shape, as illustrated in FIG. 1. The firstconductivity-type semiconductor layer 115 may have a first edge S1, asecond edge S2, a third edge S3, and a fourth edge S4. Accordingly, thefirst and third edges S1 and S3 may face each other, and the second andfourth edges S2 and S4 may face each other.

The second conductivity-type semiconductor layer 125 may be asemiconductor layer doped with p-type impurities, e.g., a p-type nitridesemiconductor layer. In some example embodiments, positions of the firstconductivity-type semiconductor layer 115 and the secondconductivity-type semiconductor layer 125 may be exchanged. The firstconductivity-type semiconductor layer 115 and the secondconductivity-type semiconductor layer 125 may include a materialrepresented by a composition formula Al_(x)In_(y)Ga_((1-x-y))N (here,0≤x<1, 0≤y<1, and 0≤x+y<1). For example, the first conductivity-typesemiconductor layer 115 and the second conductivity-type semiconductorlayer 125 may include GaN, AlGaN, InGaN, or AlInGaN.

The active layer 120 may be interposed between the firstconductivity-type semiconductor layer 115 and the secondconductivity-type semiconductor layer 125. The active layer 120 may emitlight having a predetermined amount of energy, generated byelectron-hole recombination when the semiconductor light emitting device10 operates. The active layer 120 may include a material having asmaller energy bandgap than the first conductivity-type semiconductorlayer 115 and the second conductivity-type semiconductor layer 125. Forexample, when the first conductivity-type semiconductor layer 115 andthe second conductivity-type semiconductor layer 125 are a GaN-basedcompound semiconductor material, the active layer 120 may include anInGaN-based compound semiconductor material having a smaller energybandgap than GaN. In addition, the active layer 120 may have a multiplequantum well (MQW) structure, e.g., an InGaN/GaN structure, in whichquantum well layers and quantum barrier layers are alternately stacked.However, the active layer 120 is not limited thereto, and may have asingle quantum well (SQW) structure.

As illustrated in FIG. 2, the light-emitting structure 110 may include arecess region E in which the second conductivity-type semiconductorlayer 125, the active layer 120, and a portion of the firstconductivity-type semiconductor layer 115 are etched, and a mesa regionM disposed around the recess region E, e.g., the mesa region M maycompletely surround a perimeter of at least some of the recess region Ein a top view. In the drawings, the reference character “B” represents aboundary B between the recess region E and the mesa region M. An uppersurface of the mesa region M may be higher than an upper surface therecess region E. In some example embodiments, the mesa region M maybecome narrower toward a bottom thereof. Accordingly, the mesa region Mmay have an inclined side surface.

In some example embodiments, a portion of the upper surface of therecess region E may be defined as a first contact area CT1. In someexample embodiments, at least a portion of the upper surface of the mesaregion M may be defined as a second contact area CT2.

The mesa region M may be spaced apart from the first to fourth edges S1to S4, and the recess region E may be arranged between the mesa region Mand the first to fourth edges S1 to S4. In addition, a plurality ofrecess areas E having a circular shape and spaced apart from each othermay be arranged in a center portion of the light-emitting structure 110,as illustrated in FIG. 1.

The first transparent electrode layer 140 may be disposed, e.g.,directly, on the second conductivity-type semiconductor layer 125 of thelight-emitting structure 110. The first transparent electrode layer 140may be disposed at the second contact area CT2 of the secondconductivity-type semiconductor layer 125 to be electrically connectedto the second conductivity-type semiconductor layer 125.

The first insulating layer 130 may be disposed, e.g., directly, on thefirst transparent electrode layer 140. The first insulating layer 130may cover a portion of the first conductivity-type semiconductor layer115 and a portion of the second conductivity-type semiconductor layer125, e.g., the first insulating layer 130 may cover a portion of anupper surface of the first conductivity-type semiconductor layer 115 anda lateral surface of the second conductivity-type semiconductor layer125. The first insulating layer 130 may include a plurality ofthrough-holes PD disposed in the mesa region M. The first insulatinglayer 130 may partially cover the first transparent electrode layer 140in the mesa region M. In the example embodiment, the plurality ofthrough-holes PD may be arranged in a hexagonal close-packed latticepattern, but are not limited thereto. For example, the plurality ofthrough-holes PD may be arranged in various patterns, e.g., arectangular lattice pattern. Although the plurality of through-holes PDare illustrated as having circular cross-sectional areas in FIG. 1, theyare not limited thereto, e.g., the plurality of through-holes PD mayhave polygonal or ring-shaped cross-sectional areas.

In some example embodiments, the first transparent electrode layer 140may include a plurality of through-holes arranged to be shifted from theplurality of through-holes PD. In this case, the first insulating layer130 may fill the plurality of through-holes of the first transparentelectrode layer 140.

The first insulating layer 130 may be formed of a material having alower refractive index than the second conductivity-type semiconductorlayer 125. The first insulating layer 130 may include, e.g., at leastone of SiO₂, SiN, TiO₂, HfO, and MgF₂. In some example embodiments, thefirst insulating layer 130 may have a distributed Bragg reflector (DBR)structure in which insulating layers having different refractive indicesare alternately stacked.

The second transparent electrode layer 142 may be disposed on the firstinsulating layer 130 and may be in contact with the first transparentelectrode layer 140 through the plurality of through-holes PD. The firsttransparent electrode layer 140 and the second transparent electrodelayer 142 may include at least one of, e.g., indium tin oxide (ITO),zinc-doped indium tin oxide (ZITO), zinc indium oxide (ZIO), galliumindium oxide (GlO), zinc tin oxide (ZTO), fluorine-doped tin oxide(FTO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO),In₄Sn₃O₁₂, and zinc magnesium oxide (Zn_((1-x))Mg_(x)O, 0≤x≤1).

The reflective electrode layer 144 may be disposed, e.g., directly, onthe second transparent electrode layer 142, e.g., to be conformal on thesecond transparent electrode layer 142. For example, the reflectiveelectrode layer 144 and the second transparent electrode layer 142 maycompletely overlap each other. The second transparent electrode layer142 may serve to improve adhesion between the reflective electrode layer144 and the first insulating layer 130. The reflective electrode layer144 may include, e.g., Ag, Cr, Ni, Ti, Al, Rh, Ru, or a combinationthereof.

The transparent protection layer 138 may cover upper and side surfacesof the reflective electrode layer 144 to protect the reflectiveelectrode layer 144. The transparent protection layer 138 may cover aside surface of the second transparent electrode layer 142. Thetransparent protection layer 138 may include an upper portion R1covering the upper surface of the reflective electrode layer 144 andhaving a convex surface, and a side portion R2 covering the side surfaceof the reflective electrode layer 144 and the side surface of the secondtransparent electrode layer 142 and having an inclined surface, e.g.,the upper portion R1 and the side portion R2 may be in contact andcontinuous with each other. For example, as illustrated in FIG. 2, thetransparent protection layer 138 may continuously cover all exposedsurfaces of the second transparent electrode layer 142 and thereflective electrode layer 144, e.g., the second transparent electrodelayer 142 with the reflective electrode layer 144 may be enclosedbetween the transparent protection layer 138 and the first insulatinglayer 130. By forming the transparent protection layer 138, adhesion ofthe reflective electrode layer 144 may be improved, and migration of ametal element included in the reflective electrode layer 144 may besuppressed.

The first insulating layer 130, the second transparent electrode layer142, and the reflective electrode layer 144 may configure anomni-directional reflector. The omni-directional reflector may increasereflectivity of light emitted from the active layer 120, therebyimproving light extraction efficiency.

The transparent protection layer 138 may be formed of a transparent,conductive material or a transparent insulating material. Thetransparent, conductive material may include at least one of, e.g.,indium tin oxide (ITO), zinc-doped indium tin oxide (ZITO), zinc indiumoxide (ZIO), gallium indium oxide (GIO), zinc tin oxide (ZTO),fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO),gallium-doped zinc oxide (GZO), In₄Sn₃O₁₂, and zinc magnesium oxide(Zn_((1-x))Mg_(x)O, 0≤x≤1), or a conductive polymer. The transparentinsulating material may include at least one of, e.g., SiO₂, SiN, TiO₂,HfO, and MgF₂.

The second insulating layer 150 may be disposed on the transparentprotection layer 138 and the first insulating layer 130. For example, asillustrated in FIG. 2, the second insulating layer 150 may be on theupper surface of the transparent protection layer 138, and maycontinuously extend along side surfaces of the transparent protectionlayer 138 and the first insulating layer 130.

For example, referring to FIG. 3A together with FIGS. 1 and 2, when thetransparent protection layer 138 is formed of the transparent insulatingmaterial, a first opening OPa, i.e., an opening passing through thefirst insulating layer 130 and the second insulating layer 150 to exposethe first conductivity-type semiconductor layer 115, and a secondopening OPb, i.e., an opening passing through the transparent protectionlayer 138 and the second insulating layer 150 to expose the reflectiveelectrode layer 144, may be formed. The first opening OPa may expose thefirst contact area CT1 of the first conductivity-type semiconductorlayer 115, and the second opening OPb may expose a third contact areaCT3 of the reflective electrode layer 144. The first opening OPa may bedisposed in the recess region E, and the second opening OPb may bedisposed in the mesa region M.

The first connection electrode 155 n may be disposed on the secondinsulating layer 150 and electrically connected to the firstconductivity-type semiconductor layer 115 by extending onto the firstcontact area CT1 of the first conductivity-type semiconductor layer 115through the first opening OPa. The first connection electrode 155 n maybe in contact with the first contact area CT1 of the firstconductivity-type semiconductor layer 115. In some example embodiments,in order to improve contact resistance characteristics between the firstconnection electrode 155 n and the first contact area CT1 of the firstconductivity-type semiconductor layer 115, a conductive buffer layer maybe disposed between the first connection electrode 155 n and the firstcontact area CT1 of the first conductivity-type semiconductor layer 115.

The second connection electrode 155 p may be disposed on the secondinsulating layer 150 and electrically connected to the reflectiveelectrode layer 144 by extending onto the third contact area CT3 of thereflective electrode layer 144 through the second opening OPb.Accordingly, the second connection electrode 155 p may be electricallyconnected to the second conductivity-type semiconductor layer 125 viathe reflective electrode layer 144.

In another example, referring to FIG. 3B together with FIGS. 1 and 2,when the transparent protection layer 138 is formed of the transparent,conductive material, a second opening OPb′ passing through the secondinsulating layer 150 to expose a third contact area CT3′ of thetransparent protection layer 138 may be formed, unlike that illustratedin FIG. 3A. In other words, the second opening OPb′ may pass through thesecond insulating layer 150 to directly contact the transparentprotection layer 138 (i.e., without passing through the transparentprotection layer 138). The first opening OPa may be disposed in therecess region E, and the second opening OPb′ may be disposed in the mesaregion M.

Referring back to FIG. 2, the first connection electrode 155 n may bedisposed on the second insulating layer 150 and electrically connectedto the first conductivity-type semiconductor layer 115 by extending ontothe first contact area CT1 of the first conductivity-type semiconductorlayer 115 through the first opening OPa. The first connection electrode155 n may be in contact with the first contact area CT1 of the firstconductivity-type semiconductor layer 115. In some example embodiments,a conductive buffer pattern may be formed between the first connectionelectrode 155 n and the first contact area CT1 of the firstconductivity-type semiconductor layer 115 in order to improve contactresistance characteristics between the first connection electrode 155 nand the first contact area CT1 of the first conductivity-typesemiconductor layer 115.

The second connection electrode 155 p may be disposed on the secondinsulating layer 150 and electrically connected to the reflectiveelectrode layer 144 by extending onto the third contact area CT3 of thereflective electrode layer 144 through the second opening OPb.Accordingly, the second connection electrode 155 p may be electricallyconnected to the second conductivity-type semiconductor layer 125 viathe reflective electrode layer 144.

The first connection electrode 155 n and the second connection electrode155 p may be disposed on the second insulating layer 150, formed of thesame material, and spaced apart from each other. For example, the firstconnection electrode 155 n and the second connection electrode 155 p maybe formed of a material including at least one of Al, Au, W, Pt, Si, Ir,Ag, Cu, Ni, Ti, Cr, and an alloy thereof. In a plan view, the firstconnection electrode 155 n may be adjacent to the first edge S1, and thesecond connection electrode 155 p may be adjacent to the third edge S3.

The third insulating layer 160 may include a third opening 160 a and afourth opening 160 b on the first connection electrode 155 n and thesecond connection electrode 155 p, respectively. The third opening 160 amay expose a fourth contact area CT4 of the first connection electrode155 n, and the fourth opening 160 b may expose a fifth contact area CT5of the second connection electrode 155 p.

The first electrode pad 165 n may be disposed on the fourth contact areaCT4 of the first connection electrode 155 n, and the second electrodepad 165 p may be disposed on the fifth contact area CT5 of the secondconnection electrode 155 p. The first solder pillar 170 n may bedisposed on the first electrode pad 165 n, and the second solder pillar170 p may be disposed on the second electrode pad 165 p. The first andsecond solder pillars 170 n and 170 p may be formed of a conductivematerial, e.g., Sn or AuSn.

A molding portion 172 may cover side surfaces of the first and secondsolder pillars 170 n and 170 p. The molding portion 172 may includelight-reflective powder, e.g., TiO₂ or Al₂O₃. An upper surface of themolding portion 172 may be lower than upper surfaces of the first andsecond solder pillars 170 n and 170 p.

FIGS. 4 and 5 are cross-sectional views schematically illustratingsemiconductor light emitting devices according to modified exampleembodiments. Since the semiconductor light emitting devices illustratedin FIGS. 4 and 5 have similar structures to the semiconductor lightemitting device illustrated in FIG. 2, differences therebetween willmainly be explained.

Referring to FIG. 4, the reflective electrode layer 144 of thesemiconductor light emitting device may be disposed directly on thefirst insulating layer 130, unlike that illustrated in FIG. 2. That is,the second transparent electrode layer 142 illustrated in FIG. 2 may notbe formed in the example embodiment.

Referring to FIG. 5, the semiconductor light emitting device may furtherinclude a capping electrode layer 146 disposed on the reflectiveelectrode layer 144, unlike the semiconductor light emitting deviceillustrated in FIG. 2. The capping electrode layer 146 may have amultilayer structure in which Ti and Ni are alternately stacked. Thecapping electrode layer 146 may have, e.g., a Ti/Ni/Ti/Ni/Ti multilayerstructure.

FIG. 6 is a cross-sectional view schematically illustrating asemiconductor light emitting device according to another modifiedexample embodiment.

Referring to FIG. 6, the semiconductor light emitting device may includea plurality of light-emitting structures 110 disposed on the substrate105 and separated by an isolation region ISO in which the firstconductivity-type semiconductor layer 115 is removed. In the isolationregion ISO, the first insulating layer 130 may be in contact with thefront surface 105 s 1 of the substrate 105.

The plurality of light-emitting structures 110 may be electricallyconnected in series. The semiconductor light emitting device may furtherinclude an interconnection part 155 c disposed on the isolation regionISO and connecting a first connection electrode 155 n of a firstlight-emitting structure 110 among the plurality of light-emittingstructures 110 to a second connection electrode 155 p of a secondlight-emitting structure 110 disposed adjacent to the firstlight-emitting structure 110.

Next, a method of fabricating a semiconductor light emitting device 10according to an example embodiment will be described with reference toFIGS. 7 to 20. FIGS. 7, 9, 11, 13, 15, 17, and 19 are plan viewsschematically illustrating the method of fabricating the semiconductorlight emitting device 10 according to the example embodiment, and FIGS.8 10, 12, 14, 16, 18, and 20 are cross-sectional views taken along lineI-I′ of FIGS. 7, 9, 11, 13, 15, 17, and 19, respectively.

Referring to FIGS. 7 and 8, the light-emitting structure 110 may beformed on the substrate 105. The substrate 105 may be formed of, e.g.,sapphire, Si, SiC, MgAl₂O₄, MgO, LiAlO₂, LiGaO₂, or GaN. The substrate105 may include the front surface 105 s 1 and the rear surface 105 s 2opposed to the front surface 105 s 1.

In some example embodiments, a concavo-convex structure may be formed onthe front surface 105 s 1 of the substrate 105. In some exampleembodiments, the concavo-convex structure may not be formed on the frontsurface 105 s 1 of the substrate 105.

The light-emitting structure 110 may be formed on the front surface 105s 1 of the substrate 105. The light-emitting structure 110 may be formedin a plurality of layers formed by a metal organic chemical vapordeposition (MOCVD) process, a hydride vapor phase epitaxy (HVPE)process, a molecular beam epitaxy (MBE) process, or the like. Forexample, the light-emitting structure 110 may include the firstconductivity-type semiconductor layer 115, the active layer 120, and thesecond conductivity-type semiconductor layer 125, sequentially formed onthe front surface 105 s 1 of the substrate 105. The firstconductivity-type semiconductor layer 115 may have a differentconductivity type from the second conductivity-type semiconductor layer125. For example, the first conductivity-type semiconductor layer 115may have n-type conductivity, and the second conductivity-typesemiconductor layer 125 may have p-type conductivity. In addition, thefirst transparent electrode layer 140 may be formed on thelight-emitting structure 110.

Referring to FIGS. 9 and 10, the first transparent electrode layer 140,the second conductivity-type semiconductor layer 125, the active layer120, and a portion of the first conductivity-type semiconductor layer115 may be etched using a photolithography and etching process.Accordingly, the light-emitting structure 110 may include the recessregion E, in which the second conductivity-type semiconductor layer 125,the active layer 120, and the portion of the first conductivity-typesemiconductor layer 115 are removed, and the mesa region M disposedaround the recess region E (FIG. 9). The mesa region M may be defined asa region in which the second conductivity-type semiconductor layer 125,the active layer 120, and the first conductivity-type semiconductorlayer 115 are not etched. The mesa region M may have a relativelyprotruding shape compared to the recess region E (FIG. 10). The recessregion E may be referred to as an etched region.

Referring to FIGS. 11 and 12, the first insulating layer 130 includingthe plurality of through-holes PD may be formed on the light-emittingstructure 110. The plurality of through-holes PD of the first insulatinglayer 130 may partially expose the first transparent electrode layer140. The plurality of through-holes PD may be disposed in the mesaregion M.

Referring to FIGS. 13 and 14, the second transparent electrode layer 142and the reflective electrode layer 144 may be formed on the firstinsulating layer 130. The second transparent electrode layer 142 and thereflective electrode layer 144 may be formed in the mesa region M and ona portion of the first insulating layer 130.

Referring to FIGS. 15 and 16, the transparent protection layer 138 maybe formed on the reflective electrode layer 144. The transparentprotection layer 138 may cover upper and side surfaces of the reflectiveelectrode layer 144 and the side surface of the second transparentelectrode layer 142. The transparent protection layer 138 may partiallycover the first insulating layer 130 adjacent to the reflectiveelectrode layer 144. The transparent protection layer 138 may be formed,for example, in a physical deposition process, e.g., sputtering, afterforming a photoresist pattern exposing an area at which the transparentprotection layer 138 is to be formed.

Referring to FIGS. 17 and 18, the second insulating layer 150 may beformed on the first insulating layer 130 and the transparent protectionlayer 138. The first opening OPa passing through the first insulatinglayer 130 and the second insulating layer 150 to partially expose thefirst conductivity-type semiconductor layer 115 in the recess region E,and the second opening OPb passing through the transparent protectionlayer 138 and the second insulating layer 150 to partially expose thereflective electrode layer 144 in the mesa region M, may be formed. Asurface of the first conductivity-type semiconductor layer 115 exposedby the first opening OPa may be referred to as a first contact area CT1,and a surface of the reflective electrode layer 144 exposed by thesecond opening OPb may be referred to as a third contact area CT3.

Referring to FIGS. 19 and 20, the first connection electrode 155 n andthe second connection electrode 155 p may be formed on the substrate 105including the second insulating layer 150. The formation of the firstconnection electrode 155 n and the second connection electrode 155 p mayinclude forming a conductive material layer on the substrate 105including the second insulating layer 150 and partially etching theconductive material layer using a photolithography and etching process.Since the first connection electrode 155 n and the second connectionelectrode 155 p are simultaneously formed in a single process, they areformed of the same material. The first connection electrode 155 n andthe second connection electrode 155 p may have the same thickness.

The first connection electrode 155 n may be electrically connected tothe first contact area CT1 of the first conductivity-type semiconductorlayer 115. The second connection electrode 155 p may be electricallyconnected to the third contact area CT3 of the reflective electrodelayer 144.

Referring again to FIGS. 1 and 2, the third insulating layer 160including the third opening 160 a and the fourth opening 160 b may beformed on the substrate 105 including the first connection electrode 155n and the second connection electrode 155 p. The third opening 160 a ofthe third insulating layer 160 may expose a portion of the firstconnection electrode 155 n, and the fourth opening 160 b of the thirdinsulating layer 160 may expose a portion of the second connectionelectrode 155 p.

The portion of the first connection electrode 155 n exposed by the thirdopening 160 a of the third insulating layer 160 may be referred to asthe fourth contact area CT4, and the portion of the second connectionelectrode 155 p exposed by the fourth opening 160 b of the thirdinsulating layer 160 may be referred to as the fifth contact area CT5.The first and second electrode pads 165 n and 165 p may be formed on thesubstrate 105 including the third insulating layer 160. The firstelectrode pad 165 n may be formed on the fourth contact area CT4 of thefirst connection electrode 155 n, and the second electrode pad 165 p maybe formed on the fifth contact area CT5 of the second connectionelectrode 155 p. The first and second electrode pads 165 n and 165 p maybe under bump metallurgy (UBM) layers. In some example embodiments, thenumber and arrangement of the first and second electrode pads 165 n and165 p may be variously modified.

The first and second solder pillars 170 n and 170 p may be formed on thesubstrate 105 including the first and second electrode pads 165 n and165 p. The first solder pillar 170 n may be formed on the firstelectrode pad 165 n, and the second solder pillar 170 p may be formed onthe second electrode pad 165 p.

The molding portion 172 covering side surfaces of the first and secondsolder pillars 170 n and 170 p may be formed. The molding portion 172may include light-reflective powder, e.g., TiO₂ or Al₂O₃.

The semiconductor light emitting device 10 as described above may becommercialized in package form. Hereinafter, an example of thesemiconductor light emitting device 10 applied to a package will bedescribed with reference to FIG. 21. FIG. 21 is a cross-sectional viewschematically illustrating an example of a package including asemiconductor light emitting device according to an example embodiment.

Referring to FIG. 21A, a semiconductor light emitting device package1000 may include a semiconductor light emitting device 1001 as a lightsource, a package body 1002, a pair of lead frames 1010, and anencapsulant 1005. Here, the semiconductor light emitting device 1001 maybe the semiconductor light emitting device 10 illustrated in FIGS. 1 to6, and detailed descriptions thereof will be omitted.

The semiconductor light emitting device 1001 may be mounted on the leadframes 1010 and electrically connected to the lead frames 1010. The pairof lead frames 1010 may include a first lead frame 1012 and a secondlead frame 1014. Referring to FIGS. 2 and 21, the semiconductor lightemitting device 1001 may be connected to the first lead frame 1012 andthe second lead frame 1014 by the first and second solder pillars 170 nand 170 p (of FIG. 2).

The package body 1002 may have a reflective cup to enhance lightreflection efficiency and light extraction efficiency. The encapsulant1005 formed of a light-transmissive material may be formed in thereflective cup to encapsulate the semiconductor light emitting device1001. The encapsulant 1005 may include a wavelength conversion material,e.g., a fluorescent material or a quantum dot.

By way of summation and review, as set forth above, a semiconductorlight emitting device having improved luminous flux and reliability canbe provided. That is, according to embodiments, the semiconductor lightemitting device may include a p-type omnidirectional reflector (ODR)having a structure in which a thin transparent conductive oxide adhesionlayer is interposed, as an adhesion layer, between a reflective metal,e.g., silver, and a dielectric material, with a transparentconductive/insulating material covering upper and side surfaces of thereflective metal. Accordingly, reflectance and light emission efficiencyare increased, while peeling of the reflective metal or migrationthereof can be suppressed.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A semiconductor light emitting device,comprising: a light-emitting structure including a firstconductivity-type semiconductor layer, an active layer, and a secondconductivity-type semiconductor layer; a first transparent electrodelayer on the second conductivity-type semiconductor layer; a firstinsulating layer on the first transparent electrode layer, the firstinsulating layer including a plurality of through-holes; a reflectiveelectrode layer on the first insulating layer and connected to the firsttransparent electrode layer through the plurality of through-holes; anda transparent protection layer covering upper and side surfaces of thereflective electrode layer, the transparent protection layer being on aportion of the first insulating layer.
 2. The semiconductor lightemitting device as claimed in claim 1, wherein the transparentprotection layer includes: an upper portion covering an upper surface ofthe reflective electrode layer, the upper portion having a convexsurface; and a side portion covering a side surface of the reflectiveelectrode layer, the side portion having an inclined surface.
 3. Thesemiconductor light emitting device as claimed in claim 1, wherein thetransparent protection layer includes a transparent insulating material.4. The semiconductor light emitting device as claimed in claim 1,wherein the transparent protection layer includes a transparentconductive material.
 5. The semiconductor light emitting device asclaimed in claim 1, wherein the first insulating layer includes at leastone of SiO₂, SiN, TiO₂, HfO, and MgF₂.
 6. The semiconductor lightemitting device as claimed in claim 1, wherein the first insulatinglayer has a distributed Bragg reflector (DBR) structure in whichinsulating layers having different refractive indices are alternatelystacked.
 7. The semiconductor light emitting device as claimed in claim1, wherein the reflective electrode layer includes Ag, Cr, Ni, Ti, Al,Rh, Ru, or a combination thereof.
 8. The semiconductor light emittingdevice as claimed in claim 1, further comprising a second transparentelectrode layer between the first insulating layer and the reflectiveelectrode layer.
 9. The semiconductor light emitting device as claimedin claim 8, wherein the second transparent electrode layer is in contactwith the first transparent electrode layer through the plurality ofthrough-holes.
 10. The semiconductor light emitting device as claimed inclaim 1, further comprising a capping electrode layer between thereflective electrode layer and the transparent protection layer.
 11. Asemiconductor light emitting device, comprising: a light-emittingstructure having a laminate structure of a first conductivity-typesemiconductor layer, an active layer, and a second conductivity-typesemiconductor layer, the light-emitting structure including: a recessregion in which the second conductivity-type semiconductor layer, theactive layer, and a portion of the first conductivity-type semiconductorlayer are etched, and a mesa region adjacent to the recess region; afirst transparent electrode layer on the second conductivity-typesemiconductor layer; a first insulating layer covering the firsttransparent electrode layer, the first insulating layer including aplurality of through-holes in the mesa region; a second transparentelectrode layer on the first insulating layer and in contact with thefirst transparent electrode layer through the plurality ofthrough-holes; a reflective electrode layer on the second transparentelectrode layer; and a transparent protection layer covering upper andside surfaces of the reflective electrode layer, the transparentprotection layer being on a portion of the first insulating layer. 12.The semiconductor light emitting device as claimed in claim 11, whereinthe transparent protection layer includes: an upper portion covering anupper surface of the reflective electrode layer, the upper portionhaving a convex surface, and a side portion covering a side surface ofthe reflective electrode layer, the side portion having an inclinedsurface.
 13. The semiconductor light emitting device as claimed in claim11, wherein the transparent protection layer includes an insulatingmaterial.
 14. The semiconductor light emitting device as claimed inclaim 11, wherein the first insulating layer has a lower refractiveindex than the second conductivity-type semiconductor layer.
 15. Thesemiconductor light emitting device as claimed in claim 11, furthercomprising a capping electrode layer between the reflective electrodelayer and the transparent protection layer.
 16. A semiconductor lightemitting device, comprising: a substrate; at least one light-emittingstructure including a first conductivity-type semiconductor layer, anactive layer, and a second conductivity-type semiconductor layer,sequentially stacked on the substrate; a first transparent electrodelayer connected to the second conductivity-type semiconductor layer; afirst insulating layer partially covering the first transparentelectrode layer; a second transparent electrode layer passing throughthe first insulating layer and connected to the first transparentelectrode layer; a reflective electrode layer connected to the secondtransparent electrode layer; a transparent protection layer coveringupper and side surfaces of the reflective electrode layer, thetransparent protection layer being on a portion of the first insulatinglayer; a first connection electrode passing through the active layer andthe second conductivity-type semiconductor layer and connected to thefirst conductivity-type semiconductor layer; and a second connectionelectrode passing through the transparent protection layer and connectedto the reflective electrode layer.
 17. The semiconductor light emittingdevice as claimed in claim 16, wherein the at least one light-emittingstructure includes a plurality of light-emitting structures on thesubstrate and electrically connected in series, the plurality oflight-emitting structures being separated by an isolation region fromwhich the first conductivity-type semiconductor layer is removed. 18.The semiconductor light emitting device as claimed in claim 17, furthercomprising: a first connection electrode connected to the firstconductivity-type semiconductor layer of a first light-emittingstructure of the plurality of light-emitting structures; a secondconnection electrode connected to the second conductivity-typesemiconductor layer of a second light-emitting structure of theplurality of light-emitting structures; and an interconnection part onthe isolation region and connecting the first and second connectionelectrodes.
 19. The semiconductor light emitting device as claimed inclaim 16, further comprising: first and second electrode padsrespectively connected to the first and second connection electrodes;first and second solder pillars respectively connected to the first andsecond electrode pads; and a molding portion covering side surfaces ofthe first and second solder pillars.
 20. The semiconductor lightemitting device as claimed in claim 19, wherein the molding portionincludes light-reflective powders.